<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Vue Learning</title>
</head>
<body>

<div id="app">
    <p>{{ total }}</p>
    <button-counter v-on:increment="incrementTotal"></button-counter>
    <button-counter v-on:increment="incrementTotal"></button-counter>
</div>

<script src="https://unpkg.com/vue"></script>
<script>
    Vue.component('button-counter', {
        template: '<button v-on:click="incrementCounter">{{ counter }}</button>',
        data: function () {
            return {
                counter: 0
            }
        },
        methods: {
            incrementCounter: function () {
                this.counter += 1;
                this.$emit('increment');
            }
        }
    });

    new Vue({
        el: '#app',
        data: {
            total: 0
        },
        methods: {
            incrementTotal: function () {
                this.total += 1;
            }
        }
    })
</script>
</body>
</html>